Fuel Injection Help Please, 74 1.8 LJet Options

[SteveL]

OK - this all started a while back with the engine dying after running for a while and getting warm. Extensive troubleshooting followed.
Here is Where I am at:
New SMP Injectors and injector seals.
Connected HF fuel pressure gauge. Fuel pressure is good.
After installing new injectors, it ran good, until I broke one of the fuel injector connector wires while buttoning things back up.
Checked out the harness, and it is pretty questionable, even if I made the repair I could see. So, bought a rebuilt harness from Bowlsby.
Installed FI harness, and while I was in there, I replaced all vacuum lines, including the manifold connector hoses, and intake manifold gaskets.
All back together, now it cranks and gives 3 outcomes:
1: No start at all
2: Fires, runs for a cycle or two, then dies
3: Fires, revs up to about 3k, then dies (throttle action makes no difference)
I have rechecked all harness connections, they are solid. Rechecked vacuum lines, they LOOK correct, but we all know that if it looked right the first time, it will still look right the second time.

Help!!!! I am in MN and only have a few more weeks before the dreaded white crap falls from the sky and ends the season.

[emerygt350]

I am sure others with 1.8 experience will give you great advice. I have heard that ljet can't take any kind of vacuum leak so that is where I would start. Can't use the old carb cleaner method if it doesn't run though... Smoke machine?

(Grew up in Minnesota so I feel for ya, no place for a 914, mom says snow possible this Saturday)

[wonkipop]

you been having this problem for a while @SteveL ?

here

http://www.914world.com/bbs2/index.php?sho...=355253&hl=

http://www.914world.com/bbs2/index.php?sho...355078&st=0

?

it sounds to me like the car is starting off the cold start valve.
but the injectors themselves are not opening.
runs out of the gas from the cold start valve and then dies.

you describe three different types of attempted starts.
is this on different days or different ambient temps/time of day?
or just three different types of behaviour at the same time of day.

it does not sound like the injectors themselves. they are new?
but maybe they are not getting a signal.

maybe someone can guide you through some methodical steps to get to the bottom of it. to check the electrical side of things.

someone will see this thread and assist.

[Big Len]

This sounds like the dual relay is kaput. I always keep an extra in the car.
Does anyone around you have a working spare? If not, I would just order one and keep it with the car.

[SteveL]

Wonkipop - yep, I've been fighting issues for a while - but the target has been moving.
I have a backup dual relay that I will install in the morning...

[djway]

There are many online L Jet manuals that are for diagnosis.
Google L-Jetronic and add type4org.com or thesamba.com
I have found it best to start at step one and test everything in order and not jump around. Rule one thing out then move to the next always saved time in the long run.
The bus guys on the Samba have a ton of great information.

[Geezer914]

Vacuum leak. I had the same problem. Do a smoke test. You tube shows how to make them for under $20.

[wonkipop]

Wonkipop - yep, I've been fighting issues for a while - but the target has been moving.
I have a backup dual relay that I will install in the morning...

i have a VW L Jet troubleshooting manual i found years ago on the net.
not saying this is your problem.
but it might be worth checking - just to tick it off methodically.
cold start injector.
given you checked and replaced all the other injectors.


the test is really simple as step 1. you pinch the fuel line into the injector. you leave everything in situ and unplug nothing. you crank and if it starts and runs then it is the CSinjector. i had to think about that and i'm guessing a leaky cold start injector causes the engine to flood? might be worth a try just to tick it off.

it does not sound like a vacuum leak, assuming you have all the hoses connected up correctly. i'm guessing you did the hose replacement methodically and have cross checked against the hose diagrams that are available (there are some up on this website). its a bit hard to do a vacuum leak test if you can't get the engine to run.
usually despite the talk of L jet being sensitive to vacuum leaks they will start and run, just poorly if there is a small leak.

ps - while these manuals are helpful, they don't necessarily cover all the bases 50 years down the track. for instance, while recommissioning mine, i could get it to start, but then it died. turned out it was running off a functioning CSinjector, but the other injectors were not opening. i'd had the injectors cleaned and tested, but in between testing and installing they had simply jammed shut again, too far gone with pintel corrosion from being laid up. no L jet manuals mentioned that in trouble shooting.
we knew the injectors were getting signal. i got hold of some new injectors and as soon as we installed them the car ran.

[timothy_nd28]

Sounds like a vacuum issue or a dual relay, hard to say. What was your fuel pressure meter saying when attempting to start?
Are you using mechanical points or these newer pointless modules?

Having fuel pressure is a good start, shows the dual relay is kinda working. We need to test the other half though.

With the ignition switch to on and the ecu connector unplugged, grab your voltmeter and test pin 10 to battery post ground, you should have 12 volts. This proves that the ecu is getting the command to turn on.

If so, test pin 10 to pin 5. Then test pin 10 to pin 16, then test pin 10 to pin 17,,, all should show 12 volts. This proves that the ECM is getting all the ground wires.

If all is good, put your meter lead back on the negative battery post, and test pins 14,15,32,33,,,all pins should show 12 volts. This proves that the dual relay is sending power thru the dropping resistor, and testing the current path is continuous thru the fuel injectors and back to the ECM.

Finally, set your meter so that it can measure resistance, keep one lead of the negative battery post, while the other is probing pin 13, report the result. This tests the temp sensor, very important!

Finally part II, measure the resistance between pin one to the negative terminal of the ignition coil, report those findings too. This is an important wire for the car to run, ignition coil sends pulses to the ECM to fire the injectors.


This will help paint a better picture of what’s going on, or at least help isolate the issue. Make sure all injectors are seated correctly. And post some pics of the engine bay.

[Van B]

What’s the latest here???

[SteveL]

Re-checked all vacuum lines.
Installed new fuel pressure regulator.
Same issue, loses fuel pressure after running 10 minutes or so.
Next is to look for a fuel line kink up by the tank or a clogged fuel sock in the tank. Just got the new fuel sock from 914Rubber today, so going to try to get to it this weekend. Unfortunately have to drain and pull the tank, so not a fun job.

[Van B]

But the fuel pump is good?

[Geezer914]

How about the harness from the relay board to the dual relay? Did you check continuity? That connects to the resistor block on the dual relay. Did you do a smoke test? I replaced the injectors with new seals and #4 was leaking. Had to use some Hylomar on the seal and it runs fine. Only found the leak with a smoke test. Don't take vacuum leaks for granted. The 1.8L will not run with vacuum leaks, ask me how I know. I was chasing the same problem for months.

[jim_hoyland]

Pull the two connectors off the dual relay. Check to see whether the wires are fully connecting.Especialllyon the left side....